This is a fix for a regressions introduced by MDL-54778. It
seems that escaped all our tests because there isn't any case
of such a dependency in core, but Daniele Cordella was facing
it within his surveypro module.
// Multiple selects can have one or more value assigned. A pipe (|) is used as a value separator
// when multiple values have to be selected at the same time.
values = value.split('|');
+ selected = [];
this.get('options').each(function() {
if (this.get('selected')) {
selected[selected.length] = this.get('value');